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Lorentz–Heaviside units (or Heaviside–Lorentz units) constitute a system of units (particularly electromagnetic units) within CGS, named for Hendrik Antoon Lorentz and Oliver Heaviside. They share with CGS-Gaussian units the property that the electric constant and magnetic constant do not appear, having been incorporated implicitly into the unit system and electromagnetic equations. Lorentz–Heaviside units may be regarded as normalizing and , while at the same time revising Maxwell's equations to use the speed of light instead. Lorentz–Heaviside units, like SI units but unlike Gaussian units, are ''rationalized'', meaning that there are no factors of appearing explicitly in Maxwell's equations.〔Kowalski, Ludwik, 1986, "(A Short History of the SI Units in Electricity, )" ''The Physics Teacher'' 24(2): 97–99. (Alternate web link (subscription required) )〕 The fact that these units are rationalized partly explains their appeal in quantum field theory: the Lagrangian underlying the theory does not have any factors of in these units.〔 Consequently Lorentz–Heaviside units differ by factors of in the definitions of the electric and magnetic fields and of electric charge. They are particularly convenient when performing calculations in spatial dimensions greater than three such as in string theory. They are often used in relativistic calculations. ==Length–Mass–Time Framework== As in the Gaussian units, the Heaviside–Lorentz units use the ''length–mass–time'' dimensions. This means that all of the electric and magnetic units are derived units, dependent on the sizes of length and force. Coulomb's equation, used to derive the unit of charge, is in the Gaussian system, and in the HLU. The unit of charge then connects to . The HLU charge is then larger than the Gaussian (see below), and the rest follow. When the dimensional analysis for the Gaussian units are used, including ε and μ are used to convert units, the result gives the conversion to and from the Heaviside–Lorentz units. For example, charge is . When one puts , , , and second, this evaluates as . This is the size of the HLU unit of charge. Because the Heaviside–Lorentz units continue to use separate electric and magnetic units, an additional constant is needed when electric and magnetic quantities appear in the same formula. As in the Gaussian system, this constant appears as the electromagnetic velocity . 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lorentz–Heaviside units」の詳細全文を読む スポンサード リンク
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